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HIV
Human Immunodeficiency Virus (HIV) is the virus that can lead to acquired immunodeficiency syndrome (AIDS). There are multiple methods used in order to diagnose an individual regarding his or her HIV status. Each of the widely used methods all have been developed using recombinant DNA. The different types of methods are the antibody test (the tests I will focus on in this Wikia Page) (including ELISA and the Western Blot), antigen tests, and the nucleic acid-based test. HIV Proteins HIV Type 1 is complex in that it encodes 15 distinct proteins (3). It is impossible to determine just one protein that the body has built an antigen for. This is why both of the following mechanisms of determining HIV Status do not solely focus on one protein. Some of the proteins found in HIV Type 1 are Gag, Env, SU, TM, Tat (the protein this Wikia will focus on), and Rev (3). ELISA And The Western Blot Both ELISA and the Western Blot are antibody tests. There is some controversy regarding these tests as they have the potential to give a false negative due to the lengthy window period. The window period can range from three weeks to six months, and in this time, it is impossible to detect a measurable amount of antibodies against HIV (2). The Enzyme-Linked Immunosorbent Assay (ELISA) dilutes an individual's serum. Following this dilution, the serum is added to a plate that contains HIV antigens and then is washed removing unwanted debris and other undesired components of the individual's serum (if HIV antibodies are present in the patient's sample, they will bind to the HIV antigens). Another antibody that is linked to an enzyme is added to the recently washed plate which specifically binds to human antibodies and then is washed again. A substrate is added to the plate and if the sample changes colors (due to the substrate-enzyme interaction) an individual can have a positive result (2). In the Western Blot method, positive and negative viral controls are added to a gel. This gel is placed in a buffer where an electrical current is present. The electrical current causes different proteins with different weights to move at different speeds along the gel. Once the viral proteins have fully separated, they are transferred to a membrane and the patient's diluted sample is added. If the patient does have HIV antibodies, they will attach to the HIV proteins (2). Tat Protein HIV Type 1 The Tat Protein can be found in both the cellular nucleolus as well as extracellularly (1). It is a regulatory protein that has functions in viral transcriptional transctivation by binding to transactivating responsive sequence (TAR). TAR is an RNA element for viral transcription initiation or elongation (1). The Tat Protein also upregulates expression for all viral genes as well as represses cellular promoters, so the host cell cannot function. Tat is essential for viral replication and it also has the ability to facilitate transport of molecules across membranes (4). Purification of the Tat Protein According to Dr. Hollman's research, he and his team purified the Tat Protein from a complex fermentation broth using an affinity membrane system (4). This system is unique in that it separates proteins based on their function. Bibliography "BioAfrica - HIV-1 TAT (Transactivating regulatory protein) sequence, structure and function information." BioAfrica - Bioinformatics in '' ''Africa - HIV, TB and other pathogens affecting Human Health in '' ''Africa. N.p., n.d. Web. 30 Sept. 2013. "Diagnosis of HIV/AIDS - Wikipedia, the free encyclopedia." Wikipedia, the '' ''free encyclopedia. N.p., n.d. Web. 30 Sept. 2013. Frankel, Alan D., and John A. T. Young. "HIV-1: Fifteen Proteins And An RNA." Annual Review of Biochemistry 67.1 (1998): 1-25. Print. Hollman, A.M., D.A. Christian, P.D. Ray, D. Galey, J. Turchan, A. Nath, and D. Bhattacharyya. "Selective Isolation And Purification Of Tat Protein Via Affinity Membrane Separation." Biotechnology progress 21.2 (2005): 451-459. Print.